JPH11159970A - Method for spraying refractory - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve adhesion of a sprayed material, by feeding a blended refractory composition prepared by mixing short organic fibers in a mixture of a refractory aggregate and a binder at a specific ratio and, after the composition is adjusted to an earth-like state by kneading the composition, feeding the composition to a nozzle with pressure, and adding a powdery accelerating agent to the composition in a force- feeding pipe. SOLUTION: A blended refractory composition is prepared by mixing short organic fibers composed of synthetic organic fibers of PVA (including vinylon), polypropylene, etc., in a mixture of a refractory aggregate composed of sintered alumina, electro- melted alumina, etc., containing zirconia, etc., as needed, and a binder composed of alumina cement, magnesia cement, etc. The lengths of the short organic fibers are adjusted to 0.5-2.0 mm and the mixing ratio of the fibers is adjusted to 0.01-1 pts.wt. against 100 pts.wt. of the mixture of the refractory aggregate and binder. At the time of spraying the refractory composition, the composition is adjusted to an earth- like state by adding 3-15 wt.% water to the composition from the outside and fed to a nozzle under pressure. While the composition is fed to the nozzle through a force- feeding pipe, a powdery accelerating agent such as the silicate of soda, slaked lime, etc., having an average particle diameter of 1-50 μm is added to the composition in the force-feeding pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refractory spraying method capable of spraying a large amount at a time and forming a thick body.

[0002]

2. Description of the Related Art Refractories used in various kinds of molten metal containers or associated equipment are repaired by spraying the refractories as wear progresses. This spraying is used not only for repairs, but also for new refractory applications.

[0003] The spraying method is roughly classified into a wet method and a dry method. In the wet method, the spraying material is adjusted in advance into a slurry and sprayed. On the other hand, in the dry method, after a powdery spraying material is pressure-fed into a nozzle, water is added and sprayed in the nozzle.

Both have advantages and disadvantages. The dry method is excellent in workability because it is not necessary to add construction water to the spray material in advance. However, due to the addition of water in the nozzle, the spraying material is sprayed in a state where it is not sufficiently mixed with water, and the unevenness of the structure results in poor adhesion rate, adhesive strength, and corrosion resistance.

[0005] The wet method can solve the above-mentioned problem by adjusting the spraying material into a slurry in advance, but on the other hand, the hardening of the spraying material progresses before construction, and the hardening of the spraying material and the clogging of the nozzle during the standby time are reduced. Easy to occur.

Therefore, there has been proposed a method in which a spraying material is adjusted to a kneaded soil state without containing a hardening agent, then passed through a nozzle, and a quick-setting agent is added in the nozzle. For example, JP
JP-A-4-61005, JP-A-61-111973 and JP-A-62-36070.

[0007]

However, even in this method of adding a quick setting agent in a nozzle, a large amount of spray and a large thickness are formed at a time, as in the case of a molten metal container or an apparatus associated therewith. In the construction that requires the formation of the construction body, the adhesion rate and the adhesive strength of the spray material are never sufficient.

[0008] Further, since the thickness of the construction body is increased, water vapor generated at the time of drying tends to be trapped, and there is a problem that drying explosion is caused by heating and drying with a rapid temperature rise.
An object of the present invention is to solve the above-mentioned conventional disadvantages in a spraying method for adding a quick-setting agent in a nozzle.

[0009]

According to the spraying method of the present invention, the total amount of the refractory aggregate and the binder is 100 parts by weight.
After adjusting the refractory composition containing 0.01 to 1 part by weight of organic short fibers into a kneaded soil, the mixture is pumped toward a nozzle, and a powder quick-setting agent is added and sprayed in a pumping tube. And

The quick setting agent added in the nozzle may be used in a liquid or powder form. However, since the liquid quick setting agent contains water and the like, it causes a decrease in the denseness of the structure of the construction body. . On the other hand, the powdery form does not have the above-mentioned disadvantages, but is inferior in dispersibility in the spraying material as compared with the liquid state, and the adhesion of the spraying material is insufficient.

On the other hand, according to the present invention, the organic short fibers are added in advance to the spraying material made of the refractory composition adjusted to the kneaded soil shape, and then the powdery quick setting agent is added in the pressure pipe. It is known that the addition of organic short fibers improves the adhesion of the spraying material. However, according to the present invention, the adhesion of the spraying material is improved by using in combination with the powdery quick setting agent added in the nozzle. Dramatically improved. This effect according to the present invention is considered to be due to the following reasons.

[0012] Unlike the liquid quick-setting agent, the powder quick-setting agent added to the nozzle reaches the work surface without being sufficiently dissolved and dispersed in the spray material, and is scattered throughout the spray-formed body. Since the cohesive hardening strength of the portion where the powder quick-setting agent is present is larger than that of the other portions, one end of the organic short fiber is firmly held in the portion where the powder quick-setting agent is present.

The organic short fiber has a long shape, and one end of the short fiber is firmly held, so that the Susa effect of the fiber acts on the entire structure of the construction body. As a result, it effectively acts on the adhesion of the spray material, and particularly on the prevention of sagging that is observed when obtaining a thick construction body.

In the case of the liquid quick-setting agent, the dispersibility in the spraying material is high, the cohesive hardening strength by the quick-setting agent is uniform in the structure of the construction body, and the holding strength of the organic short fibers is inferior to that. The effect of the invention cannot be obtained.

[0015] The construction obtained according to the present invention also has an excellent effect on drying. This is because the quick-setting agent is powdery, the quick-setting agent is scattered in the construction body structure, and the difference in the density of the refractory structure is large between the position where the quick-setting agent is present and the position where it is not, After the water vapor generated by heating and drying is concentrated at the above-mentioned small density portion in the refractory structure,
It is considered that this easily escapes outside the construction body through the voids formed by the organic short fibers.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the spraying material used in the present invention, specific examples of refractory aggregate include sintered alumina, electrofused alumina, shale, mullite, pyroxene, chamotte, andalusite, clay and silica. Stone, sintered magnesia, electrofused magnesia, sintered magnesia-calcia, electrofused magnesia-calcia, electrofused Al ₂ O ₃ —MgO spinel, sintered A
l ₂ O ₃ -MgO spinel, chromite, bauxite,
Main material is sillimanite, zircon, etc.
Zirconia, zircon, carbon, graphite, silicon carbide, clay,
Combine volatile silica and the like. Among them, sintered or electrofused alumina, magnesia, magnesia-calcia, A
It is preferable that the l ₂ O ₃ -MgO spinel mainly.

It is more preferable to use calcined alumina as a part of the refractory aggregate. The calcined alumina is obtained by converting aluminum hydroxide obtained by the Bayer method to a relatively low temperature of 1000 to 15;
Ultrafine particles having an average particle size of 10 μm or less obtained by firing at about 00 ° C. Because the particle surface is more chemically active than sintered alumina usually fired at an ultra-high temperature of 1700 ° C. or more, and to promote coagulation hardening by a quick-setting agent,
The holding strength of the organic short fibers is increased, and the adhesion of the spray material is further improved.

When calcined alumina is used, the ratio of calcined alumina to 100% by weight of the refractory aggregate is preferably 1 to 20% by weight. If it is less than 1% by weight, the above effect is poor,
If it exceeds 20% by weight, the viscosity of the spray material becomes too high,
Poor pumpability and adhesion.

As the binder, for example, alumina cement, magnesia cement, Portland cement and the like can be used. Assuming that the total amount of the refractory aggregate and the binder is 100% by weight, the preferred ratio of the binder is 1 to 15% by weight.

The organic short fibers include, for example, PVA (including vinylon), polypropylene, nylon, polyethylene,
Synthetic organic fibers such as acrylic and polyester. The dimensions are preferably 0.5 to 20 mm in length. The addition ratio is
0.01 to 1 part by weight, more preferably 0.01 to 0.1 part by weight, based on 100 parts by weight of the total amount of the refractory aggregate and the binder.
5 parts by weight. If the amount is less than 0.01 part by weight, the effect of the present invention cannot be obtained. If the amount exceeds 1 part by weight, the corrosion resistance of the sprayed construction decreases.

As in the case of general amorphous refractories, a combination of a dispersant, a water reducing agent, metal powder, a curing retarder, a curing accelerator, pitches and the like may be used. Specific examples of the dispersant include sodium tripolyphosphate, sodium hexametaphosphate, sodium polyacrylate, sodium polyacrylate, polycarboxylic acid, and sodium ligninsulfonate. The addition amount is preferably 0.01 to 1 part by weight based on 100 parts by weight of the total amount of the refractory aggregate and the binder.
The metal powder is preferably Al, Si, Mg or an alloy thereof, and the amount of the metal powder is, for example, 1 to 7% by weight based on the outer diameter of the refractory aggregate.

At the time of spraying, about 3 to 15% by weight of water is externally added to the refractory composition composition described above, kneaded, adjusted to a kneaded soil form, and then fed to a nozzle under pressure. The optimum flow value of the refractory blend composition adjusted to a kneaded earth shape is an upper end inner diameter of 50 mm, a lower end inner diameter of 100 mm,
Pour immediately after kneading into a cone-shaped form having a height of 150 mm, and then withdraw the cone-shaped form upward, and after 15 taps, the spread of the refractory composition is 110 mm or more.
It is less than 80 mm.

Specific examples of the powder quick-setting agent added in the feed tube include sodium silicate, slaked lime, calcium oxide, magnesium oxide, sodium phosphate, sodium aluminate, potassium aluminate, and calcium aluminates.

The average particle size of the powdery quick-setting admixture is 1 to 50 μm
Is preferred. This particle size can be measured, for example, by a radar diffraction method. If the particle size is too small, the effect of preventing adhesion is insufficient, probably because the particles are dissolved and dispersed and are not scattered in the construction body. Conversely, if the particle size is too large, it does not dissolve appropriately, and in this case also, the adhesion tends to decrease. It is preferable to adjust the addition speed of the powdery quick setting agent so that the addition speed is 0.3 to 5% by weight based on 100 parts by weight of the refractory composition composition in the form of a kneaded soil containing construction water.

FIG. 1 schematically shows a spraying device used in the present invention. A quick-setting agent supply pipe (3) is connected to a pressure-feeding pipe composed of a spray nozzle (2) and a pressure-feeding hose (1) connected to the rear thereof, so that the quick-setting agent is added to the spray material in the pressure-feeding pipe. I have. (4) is a spray construction body. Although not shown in the drawing, the supply of the quick setting agent is performed together with the compressed air to promote the mixing of the spray material and the quick setting agent. Further, the material pumping system includes a squeeze type, a screw type, a piston type and the like, and a piston type which can obtain a high pressure during the pressure feeding is preferable.

The connection point of the quick-setting agent supply pipe (3) to the pressure feed pipe is not particularly limited. In the figure, it is provided in the vicinity of the spray nozzle (2), but is not limited to this, and may be connected to, for example, the spray nozzle (2) or the pressure feeding hose (1) according to the working environment.

[0027]

EXAMPLES In each of the following examples, a spraying apparatus using a piston type pump was used to apply a refractory blended composition prepared in the form of kneaded soil to a vertical wall made of high alumina refractory.
It was sprayed at a rate of 0 to 80 kg / min. The hardener is
In the vicinity of the nozzle tip, the air was added together with the auxiliary compressed air at a ratio of about 0.7 to 1% by weight to the above-mentioned fireproof composition. Table 1 shows the quick setting agents used in each example. Table 2 shows the refractory compound compositions used in the examples of the present invention and the comparative examples, and the results of their spray tests.

[0028]

[Table 1]

[0029]

[Table 2] The test method is as follows. Adhesion; 500 mm distance from nozzle tip to sprayed surface
In order to form a 180mm thick construction body.
0 kg was sprayed, and the adhesion rate was determined.

Corrosion resistance; 110 ° C.
After heating and drying for × 24 hours, the erosion size was measured by a rotary erosion test using molten iron as a solvent, and the erosion size of the sprayed construction according to Comparative Example 5 was indicated by an index with 100 being the erosion size. The smaller the value, the better the corrosion resistance.

Drying property: Heat drying was carried out by rapid temperature rise with a gas burner, and the presence or absence of dry explosion was confirmed. Actual machine test: After using a hot metal ladle lined with an amorphous refractory of alumina-silicon carbide-carbonaceous material, spray lining repair of the liner was performed, and adhesion and durability were confirmed.

In the method according to the embodiment of the present invention, there was almost no dripping of the sprayed material, a construction body having a thickness of 180 mm was reliably formed, and an excellent effect on durability was obtained. Further, in particular, in the embodiment in which calcined alumina is partially contained as the fire-resistant aggregate of the spray material, the adhesion is further improved. The construction body obtained according to the embodiment of the present invention has excellent drying properties.
No explosion occurred during drying with a rapid rise in temperature.

On the other hand, Comparative Example 1 was inferior in adhesiveness and drying property because the liquid quick-setting agent was used and no organic short fiber was added. In Comparative Examples 2 and 3, the organic short fibers were added to the spray material, but the use of the liquid quick-setting agent significantly improved the adhesion and drying properties as compared with the Examples of the present invention. Not something. Comparative Example 4
Uses a powder quick-setting agent, but is inferior in both adhesiveness and dryness due to the lack of added organic short fibers. Further, even in the case of using a powder quick-setting agent and adding organic short fibers, Comparative Example 5 in which the amount of added organic short fibers is too large is inferior in corrosion resistance.

The objects of spraying construction according to the present invention are blast furnace gutters,
Mixed iron cars, hot metal pots, converters, electric furnaces, molten steel pots, induction furnaces, vacuum degassing furnaces, furnace lids, various gas injection lances for molten metal,
Examples include a molten metal container such as a hood for molten metal or a device associated therewith, as well as various high-temperature atmosphere furnaces, incinerators, boilers, and chemical industrial furnaces.

[0035]

[Effect] According to the spraying method of the present invention, even when spraying a large amount at a time, dripping is hardly observed, a high adhesion rate is exhibited, and a thick-walled structure is formed densely and quickly. It is possible to do. In addition, it is excellent in drying property, and there is no fear of dry explosion even in a construction body having a large thickness. As a result, the effects are extremely large, such as extending the life of the construction body and improving the spraying efficiency.

[Brief description of the drawings]

FIG. 1 schematically shows an example of a spraying apparatus used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pumping hose 2 Spray nozzle 3 Quick-setting agent supply pipe 4 Spray construction

Claims (3)

[Claims] 1. A fire-resistant composition obtained by adding 0.01 to 1 part by weight of organic short fibers to a total amount of 100 parts by weight of a fire-resistant aggregate and a binder is kneaded, and then fed to a nozzle. A method of spraying refractories, characterized in that a powdery quick setting agent is added and sprayed in a pressure pipe. 2. The powder quick-setting agent has an average particle size of 1 to 50 μm.
The method for spraying refractories according to claim 1, wherein m is m. 3. 1 to 20% by weight of the refractory aggregate of 100% by weight.
3. The method for spraying refractories according to claim 1, wherein the weight% is calcined alumina.